Tag Archives: information

One of the most common areas of practice that clients question is the need for physical examination of pets by the veterinarian. I feel that there’s a lot of misunderstood reasoning on both sides of the question. I’d like to try to offer some clear, straight talk about why examinations are important and why they happen when they do.

There are legal requirements that come into play first. According to Michigan’s veterinary practice law, vets have to know a patient well enough to make a diagnosis and/or a plan for treatment and health care. Michigan does not state how often that has to be done. Nationally, veterinarians generally feel that a yearly exam is the minimum to satisfy this requirement. The knowledge of a patient’s medical status is called the “Veterinarian-Client-Patient Relationship.” The VCPR has to be current for veterinarians to legally prescribe medications of any kind or treatments.

We can now focus on the reasons pets need examinations. One of my professors in veterinary school said, “Nothing compares to the value of a good physical exam.” What he meant was that a ton of important information is gained from a thorough examination.

Our pets rely on us to know when something is wrong. They can’t talk, and instinct tells them to hide their illnesses. Pets can seem normal when they’re actually very sick. We have only history and examination to get us started on a path to healing.

A thorough physical exam will check an animal over from nose to tail. We evaluate eyes, ears, mouth, skin, body condition, heart, lungs, internal organs, muscles and bones, general attitude, hydration status, lymph nodes, and pain score. (Our clients have the exact list on the yellow carbon copy of the exam sheet. It’s the little numbered list on the right hand side.)

It’s common for us to find something out of the normal range. It might be body weight, or yucky ears, or bad teeth. We can find tumors in the belly, arthritis, cataracts, skin growths, heart problems, or fleas. I’ve found completely unnoticed problems that were very important to the health of the pet. Good physical exams let us identify problems when they are small and easier to fix. We can really make a difference when we know what’s happening with our patients BEFORE a crisis.

By far the hottest area of contention is the need to examine pets before vaccinating them. Most people understand the need for sick pet physical examinations, but when apparently healthy pets come in ‘for their shots’ it’s tougher to understand.

For way, way too long, veterinarians depended on vaccines to be the reason pets were brought to the hospital. The true reason was to be able to examine the pet, but we didn’t explain it that way. We now understand that vaccines shouldn’t be taken lightly, and the exams are more important than vaccines. Vaccines, like all medications or treatments, have potential side effects. These risks may be higher if a patient has another problem that the owner or the vet are unaware of.

This summer, I saw a patient for vaccines that was generally fine according to the owner. I found that all of her lymph nodes were enlarged on the physical exam, and that turned out to be cancer. It would have been wrong and potentially harmful to vaccinate that dog, and if I hadn’t examined her I wouldn’t have known that. It’s an extreme example, but it holds up.

Any pet with an infection (ears, dental, skin) may not be healthy enough for vaccines. Giving vaccines could cause harm, which violates the oath we took to help our patients. I’ll tell you bluntly: if I gave a vaccine to a sick pet, *my* butt would be on the line for causing harm. I’m not taking that risk, and I won’t play recklessly with your pet’s health. It’s not fair to the pet or clients.

Problems have a starting point. People get colds at random times, or flu, or sick for other reasons. Pets are no different. We know that time moves more quickly for pets, especially as they get older (think ‘dog years’). It’s honestly just bad practice to skip the exam before vaccinating or treating a pet, even if there was an exam recently. We have to make sure that we know what’s happening today before administering vaccines or any other treatment.

Annual or twice-yearly exams are the best way you and your veterinarian have to know your pet’s true health status. The exam is the single most important thing you can have done to help your pet stay healthy and happy for as long as possible.

Labwork Part 2 – The Complete Blood Count

This week I’m going to cover the complete blood count. The post will be divided into pages, so just click the numbers at the bottom to move to the next page!

We need to start out with an explanation of the components of blood so that we can understand what is being counted. I’m going to try to draw an imperfect analogy to cooking (or at least to a recipe) to help.

Blood is soup. It’s composed of a liquid portion — the broth — which contains water, salts (electrolytes), small proteins, and antibodies. The chunks in this particular soup are cells of various types. These cells are produced in the bone marrow from larger, more complex progenitor cells. Through a series of divisions, these larger cells are transformed into red blood cells, white blood cells, and platelets. I suppose you could consider these the vegetables in the soup. Each cell type has a specific function in the body. The forms of the cells are specialized to handle these functions. The donut-cell on the left is a Red Blood Cell. The little spiny thing in the middle is a Platelet. And the fuzzy ball on the right is a White Blood Cell. This is a scanning electron microscope picture.

When we draw blood, part of the sample is put into the purple top tube. This tube prevents the blood from clotting. When we send this sample to the lab, they do two types of analysis on it.

The first is to run the blood through a special counting machine. Usually, this machine uses a laser to shine light through the cells as they pass through a very tiny tube. The effect the cells have on the light is recorded by the machine. Because the composition of the cell types differs, the machine is able to tell which type of cell has just gone through the tube. It keeps track of this and gives us a count of each type of cell. Before we had the technology to count cells with a machine, a trained individual had to look at the sample through a microscope and count the different cell types by hand. This is a picture of the laser cell concept:

The next test that’s done on the blood is to take a drop of blood and spread it in a very thin layer on a microscope slide. This is called a blood smear. The smear is dipped in special stains to color the cells. This staining allows us to distinguish parts of the cells as well as the types of the cells more readily. In some cases, we can also identify abnormalities with the structure of the cells. This visual pathology review is still done by humans. Here is a picture of how to make a blood smear, and then a picture of what it looks like under the microscope. Notice the different types of cells that can be seen there — they differ in size, shape, and color.

I’m going to spend a little time covering the two oral heartworm preventive products that we carry at Pet Authority. I’ll explain how they work in general and then give the spectrum of parasites that they cover.

Oral heartworm prevention has been around for a long time. Initially, a tablet had to be given every single day to prevent heartworms. We’ve come a long way from the Filaribits (diethylcarbamazine)! Currently, the most common type of heartworm prevention is a tablet that is given orally once a month.

As we discussed briefly in the last post, heartworms are transmitted by mosquitos. The mosquito’s bite allows heartworm larva to enter the dog’s body. They migrate to the heart and major vessels that go to the lungs. There are a few stages that the larva goes through as it makes its way from the skin bite to the heart/lungs. Heartworm prevention medications have to try to kill those larva at some point between the mosquito bite and adulthood.

The most common class of medication used to kill heartworm larva are the macrocyclic lactones. Drugs in this family came originally from a bacteria that lives in the soil. They have an extremely broad efficacy when used to treat parasites — internal and external. They are effective at relatively low doses and with a relatively high safety margin. What this means is that we’ve got a readily available, safe, effective way to prevent and treat many parasitic diseases. Ivermectin and Milbemycin are the two specific macrocyclic lactones that I will mention here.

Nearly all heartworm products out there on the market also kill a number of intestinal worms (which ones will vary by product). A second drug in the tablet may be present to accomplish this task. (Milbemycin kills intestinal worms on its own. Ivermectin -can- but not at the dosage in the heartworm preventives.) Pyrantel pamoate is the dewormer found in the most common monthly preventive tablets. The major sorts of worms that we target are hookworm, roundworm, and whipworm.

How the Drugs Work:

Basically, each dose of a macrocyclic lactone clears out a number of the heartworm larva from the dog’s system that have been ‘collected’ over the previous 30 days. We once believed that a single dose of any macrocyclic lactone was enough to clear out ALL of the larva a dog contracted in the prior 30 days. Some recent data shows that it may take as many as 3 consecutive doses to clear out the larva from an infected mosquito bite. This simply proves that what we’ve been recommending all along is the best policy: keep dogs on heartworm prevention year round. The manufacturers will guarantee that dogs are protected from heartworm if the prevention is given year-round. They help pay for treatment if there is a product failure.

The dewormers also attack and paralyze/kill the intestinal worms when they are given monthly. If the products are given year-round, the manufacturers will guarantee that pets will remain free of the intestinal worms covered by that product. It’s a great guarantee, especially since hooks and rounds are contagious to people in various ways.

Products We Carry:

Tri-Heart Plus (ivermectin/pyrantel): This is a tried-and-true formula that most people are familiar with. Given once a month, it will protect dogs from heartworm, hookworm, and roundworm. It’s a beef-flavored chewable tablet. This is essentially the same as Heartgard Plus, which is the meaty chew biscuit. We carry this because the manufacturer offers a better guarantee than the competitors and it’s priced a bit lower than Heartgard Plus. About 98% of the dogs that would willingly eat the Heartgard Plus will also eat Tri-Heart Plus. We haven’t had any problems with this product at all. More information on Tri-Heart Plus can be found here.

Interceptor (milbemycin): The milbemycin in this product takes care of heartworm, hookworm, roundworm, and whipworm. The Whipworm protection is what sets this oral chewable tablet apart. We typically dispense this product for dogs that are at risk for, or have had, whipworm. Whipworm is not contagious to people, but it’s a nuisance for dogs. It’s also exceedingly hard to clear the eggs out of the outdoor environment, so dogs that have a positive fecal test for whipworm have to be on Interceptor monthly forever to protect them from reinfection. (One of our topical products also covers for Whips, but I’ll deal with that one later on. It’s a more complicated product.) More information on Interceptor can be found here.

Choosing the Right Prevention

It’s not that difficult, really. We base our decisions first and foremost on what a patient is at risk for contracting. All dogs are at risk for contracting heartworm, whether they go outside a lot or a tiny bit. Ivermectin or Milbemycin are great options for taking care of heartworm prevention. I don’t have a preference as far as heartworms themselves are concerned.

“Stay at home” suburban dogs are at a lower risk of whipworms than a dog that goes hunting, goes to dog parks, or has a lot of wildlife (foxes, mostly) in its area. Most dogs fall into this category. Those dogs will do just fine with Tri-Heart Plus. If a patient is at risk for, or has, whipworms, we need to use Interceptor. I send Tri-Heart Plus home with most of my patients. Those at risk for whips will get Interceptor.

A note on Interceptor: If a dog is POSITIVE for heartworm, a dose of milbemycin could cause a very severe allergic/anaphylactic reaction. This can and often is life-threatening for the dog. It’s absolutely necessary for a dog to have a current negative heartworm test before starting Interceptor!

The tl;dr version is: Keep your dog on prevention year-round and pick a product based on which parasites your dog will be at risk of contracting. “Heartworm” prevention also kills intestinal parasites.